The present invention relates to portable hand held electric hair dryers and more specifically relates to a portable electric hand held hair dryer having means to reduce the hazards in normal usage.
Portable hand held electric hair dryers are one of the most popular and largest selling appliances in the world. With the increased consciousness over consumer safety and protection, studies are continuously being made to design all electric appliances so that they are as safe as possible in the hands of the consumer. There are various types of conditions which must be considered in connection with designing an appliance for maximum safety. Initially, the risk of a breakdown in the appliance which would make any exposed metal parts electrically energized so as to injure the user must be considered. With the advent of high temperature resistant plastics which are almost indestructible in normal usage, it has been possible to design most appliances so that there are no conducting parts which might be energized and located where the user could touch them. Thus, the appliance may be designed so that the rigid plastic housing or shell completely encloses the electrical components and protects the user from them.
There are, however, some appliances which are used adjacent to or in proximity to water which may serve to conduct the electricity from the interior of the portable appliance to a grounded user. This type of situation occurs in the kitchen or the bathroom when an appliance which is plugged in is accidentally dropped or immersed in water, thereby exposing the user to injury from the electricity conducted by the water.
The portable hand held electric hair dryer has particularly high risks with respect to accidental immersion in water since it is normally used in the bathroom and frequently around a tub, sink or toilet which may be filled with water. The portable hand held hair dryer is fairly simple in construction, involving a small motor driven fan, exposed resistance heating elements positioned in the path of the air produced by the fan and a switch or switches which turn the appliance on and off and provide various levels of heat. Because of the fact that the electricity is connected directly to the exposed resistance heating elements and the housing has substantial openings to provide access for the air entering and leaving the housing, water may have almost instant access to the electrically energized portions of the hair dryer when it is accidentally immersed in water. Therefore, the accidental dropping of the hair dryer into the tub, sink or toilet can immediately create a potentially lethal situation in which the user, if he is well grounded, may be electrocuted when he attempts to recover the hair dryer from the water. It should also be noted that many of the accidents associated with electric hair dryers have been a result of unsupervised small children who use the hair dryer as a toy and immerse it in the tub in which they are bathing.
The dangers associated with the hair dryer are further compounded by the dangers associated with the hair dryer even when it is shut off if it is still plugged into the power outlet. Many users assume that when and if the hair dryer falls in water when it is not turned on, it may be safely recovered. However, since most hair dryers have neither polarized plugs nor three conductor cords which might provide a measure of safety if used with the proper fused circuits, the user may be faced with the same type of hazard that would be present if the appliance were immersed with the power switch in the on position.
Many different types of solutions have been conceived by various people and companies approaching this problem of consumer safety with respect to hand held portable hair dryers. In some related product areas the elimination of risk of injury from water immersion involved completely sealing the appliances as exemplified by the toothbrush U.S. patents to Bond U.S. Pat. No. 3,278,963 and Satkunas et al U.S. Pat. No. 3,472,983 and in the electrosurgical instruments U.S. patent to Nottke U.S. Pat. No. 4,427,006. However, such an approach is impractical for the hair dryer appliance since the cost of the hair dryer would be escalated tremendously if some sort of electrically sealed heating element were to be used rather than the conventional resistance type element positioned in the stream of cool air.
Other alternative approaches involve the use of various types of sensing means which will interrupt the circuit to the hair dryer in the event that there is water associated with the internal parts of the hair dryer. Disclosures of hair dryers of this type are included in the U.S. patent to Aragaki et al U.S. Pat. No. 4,464,582 and Gilardoni et al U.S. Pat. No. 4,270,158. Another disclosure of a hair dryer having means for sensing the presence of water and disabling the hair dryer is included in the U.S. patent to Crowley, et al. U.S. Pat. No. 4,550,358 assigned to the same assignee as the instant invention.
Another prior art protective circuit for use on a hand held hair dryer is disclosed in the U.S. patent to Miffitt U.S. Pat. No. 4,029,996 which includes a means for sensing the presence of the user and for disabling the power supply when the product is not being held. Another approach to eliminating the risks associated with hand held hair dryers is shown in the U.S. patent to Yamamoto U.S. Pat. No. 4,493,975 which discloses a wall switch associated with the hair dryer which requires the user to actuate the switch when using the hair dryer and which automatically turns off the switch when the hair dryer is replaced on its supporting bracket. This approach is designed to prevent the user from inadvertently leaving the hair dryer plugged in and shut off in such a way that it might fall into water and become a hazard. The only way the user can shut off the hair dryer of the Yamamoto patent is to replace it on the support stand. All of the foregoing approaches involve fairly complex circuitry which would add considerably to the cost of a hand held hair dryer.
The U.S. patent to Bigley, et al. U.S. Pat. No. 3,766,352 is noted of interest as teaching the concept of a switch having secondary mechanism which must be actuated before the switch itself can be closed. A similar type of mechanism is contemplated as a part of the instant invention.